Metal-oxide-semiconductor field-effect transistors
The insulated-gate field-effect transistor was conceived in the 1930s by Lilienfeld and Heil. An insulatedgate transistor is distinguished by the presence of an insulator between the main control terminal and the remainder of the device. Ideally, the transistor draws no current through its gate (in practice a small leakage current on the order of 10 A to 10 A exists). This is in sharp contrast to bipolar junction transistors that require a significant base current to operate. Unfortunately, the M etal-O xide-S emiconductor F ield Effect Tansistor (MOSFET) had to wait nearly 30 years until the 1960s when manufacturing advances made the device a practical reality. Since then, the explosive growth of MOSFET utilization in every aspect of electronics has been phenomenal. The use of MOSFETs in electronics became ever more prevalent when “complementary” types of MOSFET devices were combined by Wanlass in the early 1960s to produce logic that required virtually no power except when changing state. MOSFET processes that offer complementary types of transistors are known as Complementary Metal Oxide Semiconductor (CMOS) processes, and are the foundation of the modern commodity electronics industry. The MOSFET’s primary advantages over other types of integrated devices are its mature fabrication technology, its high integration levels, its mixed analog/digital compatibility, its capability for low voltage operation, its successful scaling characteristics, and the combination of complementary MOSFETs yielding low power CMOS circuits.